JVM- jvm(java virtual machine) is a specification which does the following
         works.

1 . Loads code.
2 . Verifies code.
3 . Executes code.
4 . Provides Runtime environment in which byte code gets executed.



JVM internal architecture






JRE - jre acronym for java runtime environment  is an implementation of
         JVM. It contains set of libraries and other files that JVM uses at runtime.
         We can say JVM is a part of JRE.

     



JDK - JDK is the java development kit which contains development tools and
         JRE.




JVM, JRE and JDK all are platform dependent.

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